diff options
| author | Miklos Szeredi <mszeredi@suse.cz> | 2011-11-21 12:11:33 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-01-06 23:20:13 -0500 |
| commit | 8e8b87964bc8dc5c14b6543fc933b7725f07d3ac (patch) | |
| tree | 9a14c135741f3a8ba960ff97f060a58597604a6d /fs | |
| parent | 7ada4db88634429f4da690ad1c4eb73c93085f0c (diff) | |
| download | lwn-8e8b87964bc8dc5c14b6543fc933b7725f07d3ac.tar.gz lwn-8e8b87964bc8dc5c14b6543fc933b7725f07d3ac.zip | |
vfs: prevent remount read-only if pending removes
If there are any inodes on the super block that have been unlinked
(i_nlink == 0) but have not yet been deleted then prevent the
remounting the super block read-only.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/file_table.c | 23 | ||||
| -rw-r--r-- | fs/namespace.c | 7 | ||||
| -rw-r--r-- | fs/super.c | 4 |
3 files changed, 7 insertions, 27 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index c322794f7360..20002e39754d 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -474,29 +474,6 @@ void file_sb_list_del(struct file *file) #endif -int fs_may_remount_ro(struct super_block *sb) -{ - struct file *file; - /* Check that no files are currently opened for writing. */ - lg_global_lock(files_lglock); - do_file_list_for_each_entry(sb, file) { - struct inode *inode = file->f_path.dentry->d_inode; - - /* File with pending delete? */ - if (inode->i_nlink == 0) - goto too_bad; - - /* Writeable file? */ - if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) - goto too_bad; - } while_file_list_for_each_entry; - lg_global_unlock(files_lglock); - return 1; /* Tis' cool bro. */ -too_bad: - lg_global_unlock(files_lglock); - return 0; -} - /** * mark_files_ro - mark all files read-only * @sb: superblock in question diff --git a/fs/namespace.c b/fs/namespace.c index 98ebc78b21ab..7e6f2c9dc7c4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -449,6 +449,10 @@ int sb_prepare_remount_readonly(struct super_block *sb) struct mount *mnt; int err = 0; + /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ + if (atomic_long_read(&sb->s_remove_count)) + return -EBUSY; + br_write_lock(vfsmount_lock); list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { @@ -460,6 +464,9 @@ int sb_prepare_remount_readonly(struct super_block *sb) } } } + if (!err && atomic_long_read(&sb->s_remove_count)) + err = -EBUSY; + if (!err) { sb->s_readonly_remount = 1; smp_wmb(); diff --git a/fs/super.c b/fs/super.c index 6acc02237e3e..de41e1e46f09 100644 --- a/fs/super.c +++ b/fs/super.c @@ -729,10 +729,6 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force) retval = sb_prepare_remount_readonly(sb); if (retval) return retval; - - retval = -EBUSY; - if (!fs_may_remount_ro(sb)) - goto cancel_readonly; } } |